1. Field of the Invention
This invention generally relates to an operating device for a vehicle component assembly. More specifically, the present invention relates to an operating device that moves a movable member of a vehicle component assembly between at least two positions. The present invention especially relates to bicycle components that are actuated by a cable or other mechanical linkage.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle.
For example, the front and rear shifting assemblies are often redesigned to make them easier to operate. A shifting assembly or unit has a plurality of gears which are used on a bicycle in order to climb hills more easily, or to ride faster on flat ground. The shifting unit or assembly generally has a shift control component that the rider uses to make a shift and a shift mechanism that is linked to the shift control component by a control cable.
The shift control component has, for example, two shift levers and a cable winding mechanism that rotates via a ratchet mechanism when the shift levers are operated. The shift mechanisms come in internal and external types. An external shift mechanism has a plurality of sprockets that are set up parallel to each other and that have different numbers of teeth, and a derailleur that moves back and forth in the axial direction of the sprocket for guiding and shifting the chain between sprockets. The derailleur has a mounting component that is mounted to the bicycle frame and a chain guide component that moves with respect to the mounting component for guiding the chain in the shift direction.
With conventional shift units or assemblies, operation of one of the shift lever causes the cable winder to rotate via the ratchet mechanism in one direction by one gear. As a result, the cable is wound around the cable winder, and a shift is made by the shift mechanism from one gear to the next gear. Operation of the other shift lever causes the ratchet mechanism to be released and the cable winder to rotate in the other direction by one gear. As a result, the cable that was wound on the cable winder is played out, and a shift is made in the opposite direction by the shift mechanism.
Generally, front and rear derailleurs include a fixed member nonmovably secured to a bicycle frame, and a movable section supported to be movable relative to the fixed member. Typically, the fixed member of a front derailleur is a tubular clamping member that is secured to the seat tube. Alternatively, the fixed member of a front derailleur is sometimes coupled to the bottom bracket. A rear derailleur is fixed to the frame by a bracket axle assembly or a derailleur hanger.
The movable section of the front or rear derailleur includes a chain guide. The movable section is movable relative to the fixed member by pulling a shift control cable. In particular, the movable section and fixed member usually are interconnected through pivotal links. The control cable is connected to one of the pivotal links to apply a torque thereto, thereby causing the links to move the movable section. The control cable is fixedly coupled to the link in such a position that an operating force is applied to the control cable. This force on the cable is converted into a link swinging torque.
An internal shift mechanism, on the other hand, has a plurality of transmission mechanisms of different gear ratios that are provided inside the rear wheel hub. A controller is moved back and forth in the hub axial direction to select one of the plurality of transmission mechanisms. The internal shift mechanism is typically operated by a cable from a shifting device.
Whether an external shift mechanism or an internal shift mechanism is used, a return spring is utilized to act against the cable. In other words, when one of the levers is pushed to release the control cable, slack occurs in the control cable. The slack is taken up by the return spring. Accordingly, when the other lever is pushed, his means that the rider must push the lever against the return spring. This will cause the rider to exert additional force to not only pull the cable, but to overcome the biasing force of the return spring.
The majority of the effort expended by a rider during riding, especially during a race, goes into pedaling. Accordingly, an important evaluation of a shift unit or assembly is how much it can reduce the effort the rider must exert to operate the shift levers. In order to reduce the effort the rider must exert to operate the shift levers, the stroke of the shift levers must be shortened and their operating force reduced. However, these two requirements are at odds with each other. For example, the operating force increases if the operating stroke is shortened, and the operating stroke becomes longer if the operating force is reduced. Consequently, with a system whereby a shift is made by winding a cable by means of shift levers, satisfying both of these requirements at the same time is next to impossible.
In view of the above, there exists a need for an operating device for a vehicle component assembly which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.